The invention discloses a device for continuously replacing a side sealing plate for thin strip continuous casting. The side sealing plate is arranged on one side of a pushing rod; the other side of the pushing rod is connected with a rotator and positioned in a groove in the rotator; the groove in the vertical state is reserved in the diameter direction of the rotator for moving the pushing rod up and down; and a pushing rod locking device is arranged at the center of the circle of the rotator. In a thin strip continuous casting process, the transmission side of one of the pushing rods is locked, the side sealing plate is arranged on the working side of the pushing rod, and the other pushing rod is in a vacancy state. When the side sealing plate above needs to be replaced, the side sealing plate is arranged at the vacancy pushing rod and the pushing rod moves upward along the groove, then the two pushing rods move upward together until the lower pushing rod is locked, and then the rotator rotates to rotate the upper pushing rod to the lower side, so that the worn side sealing plate is capable of being taken down and put into a standby state. On-line continuous replacement of the side sealing plate can be realized, the production continuity of the thin strip continuous casting is improved, the production cost is reduced, and a strip steel product of the thin strip continuous casting has more cost advantages.